Update command-line tool design to support list models/repos in Model Zoo (#2746)
Update command-line tool design to support list models/repos in Model Zoo (#2746)

* refine pai code structure

* remove unused function

* move tensorflow files to a sub-package

* add docstring

* Add KMeans and RF PAI submitter

* use model type defined in runtim.model

* fix string compare

* Evaluate for PAI

* modify code

* update cli design to support model zoo list

* update doc
sql-machine-learning/sqlflow,sql-machine-learning/sqlflow,sql-machine-learning/sqlflow,sql-machine-learning/sqlflow,sql-machine-learning/sqlflow,sql-machine-learning/sqlflow